Heat the oven to 350°F and grease a 9x13-inch baking dish.
Toss the sliced apples with the brown sugar and cinnamon, then spread them in an even layer across the bottom of the dish.
Drizzle the caramel sauce evenly over the apples.
Pour the dry cake mix straight from the box over the apples and spread it into an even layer with the back of a spoon. Do not stir it into the fruit.
Slice the cold butter into thin pats and lay them across the entire surface like tiles, edge to edge, leaving no bare spots — this is what prevents dry powdery patches.
Bake for 45 to 55 minutes, until the top is golden brown and you can see the filling bubbling in the center, not just at the edges.
Let it cool for 15 minutes. Serve warm with vanilla ice cream and an extra drizzle of caramel.